Currently, filtration of air in transport compartments (e.g., bus and/or rail vehicles, etc.) is typically performed by fiber filters or rubber foam mats. Airborne particles are gradually captured from air flow within such filters, thus closing the tiny gaps between the filter fibers. In vehicles, the space available for installation of air filters can be limited, there may be high air flow rates, and may encounter small static pressure. These factors may limit the use of air filters to coarse filters and may prevent the application of filters otherwise used in buildings (e.g. bag filters having a larger size and higher air flow resistance).
Furthermore, maintenance service of these conventional air filters is typically required periodically, for example, at least four times a year. Such maintenance procedures require a skilled workforce and require that the vehicle be out of duty, thus increasing the cost for maintenance.